Imaging systems used for monitoring an area typically include mechanical components for moving an imaging device, such as a camera, to direct the camera toward an area of interest. The mechanical components provide a pan and tilt function and can be operated manually or automatically. In some instances, it is not practical to move the camera. For those instances, it would be desirable to have a device that provides the pan and tilt function without requiring physical movement of the camera.
Prisms are known to bend light. The degree of bending is a function of the wavelength of light and thus prisms are typically used to separate the various light wavelengths allowing independent studying of each wavelength of the incident light beam. In the case of white light, comprised of all visible wavelengths (e.g. all colors), a prism can separate the white light into the seven commonly referred to colors of the rainbow.
Risley prisms, which include two counter-rotating circular thin prism wedges, have been used in the ophthalmology field to steer laser beams. Since lasers are on a single wavelength, no achromatic correction is needed.
While prisms can be used to shift the direction of light, wavelength separation caused by the prisms creates distortion when the prisms are used in imaging systems. There is a need for an apparatus that can be used in conjunction with an imaging device to provide the pan and tilt functions without requiring movement of the imaging device.